Linked Lists for Technical Interviews – Full Course
5. Linked list cheat sheet
Linked list definition: A linked list is a collection of nodes representing a sequence. Each node contains data and a reference (a link) to the next and/or previous node in the sequence.
You can download this cheat sheet here.
Related algorithms and techniques
4. Linked list basics
In order to crack the questions above and others like them, you’ll need to have a strong understanding of linked lists and how they work. Let’s get into it.
3. Hard linked list interview questions
Similar to the medium section, these more difficult questions may be asked in an onsite or video call interview. You will likely be given more time if you are expected to create a full solution.
linked list interview questions
A linked list is a data structure that can store a collection of items. In other words, linked lists can be utilized to store several objects of the same type. Each unit or element of the list is referred as a node. Each node has its own data and the address of the next node. It is like a chain. Linked Lists are used to create graph and trees.
1. Easy linked list interview questions
You might be tempted to try to read all of the possible questions and memorize the solutions, but this is not feasible. Interviewers will always try to find new questions, or ones that are not available online. Instead, you should use these questions to practice the fundamental concepts of linked lists.
As you consider each question, try to replicate the conditions you’ll encounter in your interview. Begin by writing your own solution without external resources in a fixed amount of time.
If you get stuck, go ahead and look at the solutions, but then try the next one alone again. Don’t get stuck in a loop of reading as many solutions as possible! We’ve analysed dozens of questions and selected ones that are commonly asked and have clear and high quality answers.
Here are some of the easiest questions you might get asked in a coding interview. These questions are often asked during the “phone screen” stage, so you should be comfortable answering them without being able to write code or use a whiteboard.
2. Medium linked list interview questions
Here are some moderate-level questions that are often asked in a video call or onsite interview. You should be prepared to write code or sketch out the solutions on a whiteboard if asked.
4.1 What is a linked list?
A linked list is a data structure used to store a collection of data elements. In this way, it is similar to an array. However, unlike an array, the data elements in a linked list do not need to be stored contiguously in memory. Rather, each node in a linked list has a pointer or reference to the memory location of the next node in the list. This means that linked lists do not have a fixed size like arrays, and can easily grow and shrink as elements are added or removed.
Another advantage linked lists have over arrays is that inserting or removing elements from a linked list is possible in constant time, whereas removing or inserting elements into an array generally takes linear time.
Since the data elements are not stored sequentially in contiguous memory, linked lists are not as efficient as arrays at random access of elements. Indexes are commonly used to access any element in an array in constant time. Accessing an element in a linked list generally means walking the list from one node to the next. This takes linear time.
There are a number of variations on the standard singly linked list.
A doubly linked list has nodes with links to next and previous nodes, making it possible to traverse the list in either direction.
A circular linked lists last node has a link to the lists first node. This is useful for implementing certain types of circular buffers. It is also useful for implementing round-robin-type schemes.
A multi-linked list has multiple links from each node. The different links point to the “next” node based on some ordering or logical criteria. In this way, it is possible to have the list ordered on multiple properties. For example, in a movie list, there could be a link to the next movie alphabetically, another link to the next movie chronologically, and another link to the next movie by the same director. Multi-linked lists are also useful for implementing sparse matrices, where a node has a link to the next number in the row, and the next number in the column.
Java has a built-in linked list implementation called “LinkedList.” Python has a “deque” class in its collections module, which is implemented as a linked list. In the Standard Template Library (STL) in C++, there is a linked “list” class, which implements a doubly linked list.
Linked lists are made up of a string of nodes. Each node is a container which stores the data element along with a reference to the next node. The first node is known as the head of the list. This is often used as the entry point, or handle, to the linked list. The last node in the list generally has its next pointer set to null, except in circular linked lists, where the last node points to the head node.
Linked lists are mainly contrasted to arrays. Arrays have faster access time, in constant time, to access a random element through indexes. Accessing an element in a linked list takes linear time. Linked lists are faster at inserting and removing elements, which can be done in constant time if the target position of the node is known, whereas arrays take linear time. Linked lists can also grow to very large sizes more easily than arrays, as linked lists are not bound to available contiguous memory blocks as arrays are.
Queues and stacks are often implemented using linked lists, as the size of these structures is often large and dynamic. Queues and stacks also do not require random indexed access to elements, as elements are added and removed from the ends. Linked lists perform well here, as adding or removing elements from the ends of the list can be done in constant time.
